1. Field of Invention
The present invention relates to a composition of a water-repellent agent, and more particularly to a water-repellent agent used for a fabric made of cationic dyeable polyester (CDPET), which has good waterproof ability and enhanced color fastness in light.
2. Description of the Related Art
Recently, clothes have various colors and designs for user to choose. Thus, a fabric has to be dyed to present different colors. Traditionally, a polyester fabric is dyed with disperse dye. However, the disperse dye in the polyester fabric cannot bear heat, so the polyester fabric has a poor color fastness in light. Now, a cationic dyeable polyester (CDPET) fabric is presented to maintain a dye on the CDPET fabric under sunlight. However, the CDPET fabric with a light color dye will discolor easily. Therefore, some manufacturer will add ultraviolet absorbers into the CDPET fabric when the CDPET fabric is dyed to prolong the life of the dye on the CDPET fabric (i.e. to improve a color fastness in light.)
Additionally, most fabric will proceed with a water repellent finishing improving a waterproof ability and a dirt-resistance. The water repellent finishing will change a surface property of the fabric to allow the fabric to keep water and dirt out of a surface of the fabric. Thus, in one hand, the dirt cannot enter into the fabric, so the dirt on the surface of the fabric can be washed easily. In the other hand, because water also cannot enter easily into the fabric, the fabric can dry rapidly.
In one case, a CDPET fabric is immersed in a dye bath with ultraviolet absorbers first. In turn, the CDPET fabric is immersed in a dye bath with surfactant. Finally, the CDPET fabric is immersed in a water-repellent agent and then the CDPET fabric is treated by padding mangling to obtain a CDPET fabric. The water-repellent agent has a solvent being water and a solute dissolved in water. The solute comprises fluoro-acryl, toluene-2, 4-diisocyanate, 4,4-diphenylmethane diisocyanate, melamine derivatives, magnesium chloride (MgCl2) and DL malic acid, wherein the improvement comprises zinc acetate. Zinc acetate covers the dye on a surface of the fabric to prevent the dye from the sunlight to improve a color fastness in light. However, the CDPET fabric is formed by multiple fibers interweaving, so the CDPET fabric has multiple meshes. Because zinc acetate can not obstruct the intervals, water can enter into the fabric through the meshes. Thus, the CDPET fabric has poor waterproof ability.
In another case, the CDPET fabric further has isocyanate-acryl. The isocyanate-acryl obstructs the meshes of the CDPET fabric to improve the waterproof ability. However, isocyanate-acryl will refract the sunlight, so the sunlight will pass through the isocyanate-acryl. Therefore, the color fastness in light of the CDPET fabric will be decreased.
In brief, no excellent color fastness in light and waterproof ability usually exists in the CDPET fabric at the same time.
To overcome the shortcomings, the present invention provides a composition of a water-repellent agent to mitigate or obviate the aforementioned.